Is CVE-2021-27645 in the CISA KEV catalog?

No. CVE-2021-27645 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-27645?

CVE-2021-27645 has a CVSS v3 base score of 2.5 (LOW).

What is the EPSS score for CVE-2021-27645?

CVE-2021-27645 has an EPSS score of 0.37% (29th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-27645?

Upgrade glibc on debian 11 to 2.31-10 or later. Fixes are available for 3 affected products.

CVE & CISA-KEV Catalog

CVE-2021-27645

LOW

2.5

CVSS v3

NVD

Description

The nameserver caching daemon (nscd) in the GNU C Library (aka glibc or libc6) 2.29 through 2.33, when processing a request for netgroup lookup, may crash due to a double-free, potentially resulting in degraded service or Denial of Service on the local system. This is related to netgroupcache.c.

CWE-415

How to fix

Remediation Available

glibcDebian

Fixed in:2.31-10CVE-2021-27645

glibcUbuntu

Fixed in:2.27-3ubuntu1.5USN-5310-1

Fixed in:2.31-0ubuntu9.7USN-5310-1

libc6Ubuntu

Fixed in:2.27-3ubuntu1.5USN-5310-1

Fixed in:2.31-0ubuntu9.7USN-5310-1

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorLocal

Attack ComplexityHigh

Privileges RequiredLow

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityLow

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:L

Exploit Intelligence

0.37%probability of exploitation in 30 days

29thpercentile

Low risk: more likely to be exploited than 29% of all known CVEs.

References

Patch1

sourceware.org

Third-Party Advisory2

Other references2

Related Vulnerabilities

Other CWE-415 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2023-25136	Medium	6.5	90%	-	Fix
CVE-2018-0101	Critical	10.0	87%	-	Fix
CVE-2003-0545	Critical	9.8	85%	-	Fix
CVE-2019-3829	Medium	5.3	59%	-	Fix
CVE-2026-33824	Critical	9.8	56%	-	Fix
CVE-2021-3407	Medium	5.5	50%	-	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-06-09.